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Cover Home Additions & ADU: The Los Angeles Owner’s Guide
A full home addition or ADU build in Los Angeles typically runs $53,100 to $153,400 for a permitted project, and a garage conversion lands between $35,400 and $94,400. That’s the installed cost, including plans, permits, framing, electrical, plumbing, drywall, and finish work. If you’re reading this, you likely have a Cover-style addition or ADU project that went sideways, or a part of the structure – a door, a window, a mini-split line, a panel, or a roof intersection – that’s failed and needs a contractor who will actually show up and look at it. We’re Mason Remodeling Co Los Angeles, an independent contractor, not affiliated with Cover. We repair and finish what other crews couldn’t.
Which Cover Models This Applies To
Cover is a prefab ADU and addition manufacturer based in Gardena, and their panelized system uses steel framing with factory-cut openings sized for specific door and window packages. The two most common product lines we see in Los Angeles are the Cover Studio (400 to 500 square feet, single-story) and the Cover One (up to 1,200 square feet, one or two bedroom). Their wall panels arrive pre-sheathed, which means the roofline intersection, electrical chase locations, and window rough openings are all set at the factory. If a door or window fails on one of these units, you can’t just swap in a big-box replacement – the rough opening is often a nonstandard size, and the steel frame doesn’t forgive a framing adjustment the way wood does. You’ll find the Cover model plate riveted to the inside of the main electrical panel cover or stamped on the floor track near the entry door. Take a photo of that plate before you call anyone. It tells us the panel lot, the window and door package, and whether your unit carries the commercial-grade glass option or standard residential.
Styles & brands we work with
Signs Your Cover Home Additions & ADU Is Failing
- Water staining at the wall-to-roof transition: The panelized roof on a Cover unit relies on a factory gasket and field-applied sealant. After two or three Los Angeles summers, that sealant shrinks and cracks. We see this constantly on units in the Valley, where 105-degree days bake the west-facing roof edge.
- A sliding door that binds or won’t lock: The steel frame settles slightly in the first 18 months, especially on units poured over expansive soil like the clay-heavy areas around Atwater Village and Eagle Rock. The door track stays true, but the frame twists just enough to throw the strike plate out of alignment.
- Tripped breakers on a single circuit: Cover units are built tight, and the factory specs assume a specific appliance load. Add a portable AC unit during a Woodland Hills heat wave and the 20-amp kitchen circuit can’t keep up. The panel itself is usually fine – the wiring spec wasn’t sized for the actual use.
- Flaking or delaminating exterior panel joints: The vertical seams between factory panels are flashed and caulked in the field. That’s where the system fails first in coastal neighborhoods like Playa del Rey, where salt air accelerates sealant breakdown.
- Mini-split line set vibration or hissing: Cover routes the refrigerant lines through a factory chase in the wall cavity. If the chase grommet slips, the copper line rubs against the steel stud and eventually leaks. You’ll hear it as a soft hiss or a vibration buzz when the unit runs.
See the difference
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AfterReplacement Cost & What’s Included
For a full Cover home addition or ADU rebuild in Los Angeles, plan for $53,100 to $153,400 depending on the scope. A garage conversion on a Cover-style steel frame runs $35,400 to $94,400. If you’re looking at a specific failed component – a sliding door replacement, a window swap, a door panel replacement on a Cover unit – those smaller fixes typically fall between $2,360 and $7,670 for a single opening, installed. Every number we give is a written price before work starts, not a verbal ballpark that grows on the final bill. The price includes the part, freight if we can’t pull it locally, permitting when required, and our labor through inspection. We warranty the work for 365 days from the completion date. If something isn’t right, we come back and fix it at no charge.
DIY or Call Us?
You can check the model plate, photograph the damage, and clear the area around the failed section. That’s genuinely useful and saves time. What you should not do is attempt to cut into a Cover steel wall panel or rooftop joint yourself. Those panels carry structural load, and the factory chase includes electrical runs. Cutting through a steel stud or hitting a live line is a hospital trip waiting to happen, and it voids whatever warranty remains on the unit. The sealant work at roof transitions requires working off a ladder at height. That’s not a weekend job. Call us at (213) 632-5711 and we’ll send someone who knows exactly where the weak points are on these units.
FAQs
A well-installed Cover unit with proper flashing and sealant maintenance should last 30 to 50 years before needing major structural work. The finish components – doors, windows, roof sealant – typically need attention every 8 to 12 years in this climate. Coastal neighborhoods accelerate that timeline by a few years. Get an inspection before year five so small sealant failures don’t become wall cavity repairs. Call (213) 632-5711 for an honest assessment.
Most failed components on a Cover unit can be repaired or replaced without touching the rest of the structure. A binding sliding door is usually a roller and track adjustment. A leaking roof joint is a re-seal and re-flash, not a new roof. Full panel replacement is rare and only needed if water has rotted the interior sheathing or the steel has rusted through. We always quote the repair option first if it’s structurally sound. Call (213) 632-5711 for a written, line-item quote.
A door or window swap on a Cover unit takes one to two days once the part is in hand. A roof transition re-seal is a one-day job. A full interior rebuild or converted-space repair runs three to eight weeks depending on permitting and inspection scheduling with the city. We give you the timeline in writing before work begins, and we stick to it. Call (213) 632-5711 to talk through your specific scope.
We keep common door rollers, track hardware, sealants, and flashing profiles on the truck for Cover units. Larger items – replacement door panels, specific window packages, mini-split line sets – are sourced from Cover’s Gardena facility or our local suppliers, usually arriving within three to five business days. We also work with equivalent parts from KraftMaid, Cambria, and Silestone when a finish upgrade makes better sense than the original spec. Call (213) 632-5711 and tell us your model number; we’ll tell you honestly what’s on hand and what needs ordering.
Know who’s coming, know what it costs, know it’s guaranteed – everything else is just noise.
Written by Isaac Pruett, Owner, Mason Remodeling Co at Mason Remodeling Co Los Angeles, serving Los Angeles and nearby areas.
